1. Field of the Invention
The present invention is directed to the provision of a novel and unique soak or leaching tank installation which is intended to extract soluble constituents from insoluble materials, and more particularly, relates to a horizontal flow soak tank for removing soluble components, such as sugars or oligosaccharides, from beans which are in a stage of being processed. More specifically, there is disclosed a method which utilizes a novel recirculating water system in conjunction with the inventive soak apparatus or horizontal flow tank in order to leach solubles, such as sugars in the form of oligosaccharides and other potentially soluble components from insoluble materials.
In general, soak or leaching tanks and methods for leaching or extracting soluble constituents from a variety of insoluble comestible and non-comestible materials as a function in the steps of processing the materials, are well known and highly developed in the technology, and have been and are employed in broad sectors of industry for many years. Among such leaching apparatus, there are presently employed leaching systems incorporating so-called upright columns in the form of vertical towers or the like, wherein there are contained stacks of comestible, such as edible beans which are to be soaked in order to extract unwanted or undesirable soluble constituents therefrom. In order to implement the foregoing, normally, heated water or other suitable liquid solutions are filled into the tower and caused to flow downwardly through a stack or pile of the material being treated. In essence, this type of vertical leaching apparatus has proven to be somewhat problematic in the use thereof, especially when applied to comestibles, such as beans. This is because encountered leaching or soaking conditions are not always uniform between the upper and lower layers of the vertical stack of beans, and are not always uniform horizontally across the bed of materials which are to be processed, thereby occasionally resulting in an uneven leaching of soluble constituents therefrom. This non-uniformity in the soaking conditions, at times, may adversely influence the taste and physical characteristics or textures of the processed beans. Moreover, the utilization of vertical leaching columns or tower-type soak tanks causes the lower layers of the beans to be subjected to the weight of a high superimposed column or stack of beans, damaging or even crushing the lower layers of the charge of beans. Additionally, the use of a vertical column or tower structure increases the stresses encountered by the supporting floor structure, inasmuch as the weight of the beans and the soak liquid, and that of the mechanical structure of the tower itself, is concentrated over a relatively smaller surface area, and thereby requires either expensive structural reinforcements and support flooring, or necessitates having to reduce the size of the vertical soak apparatus or towers. It has also been found that vertical columns tend to restrict swelling/expansion of the beans in the lower portions of the vessel. This, resultingly, adversely affects bean yield.
Nevertheless, although the bottommost beans or layers of beans may be crushed by the weight of liquid-swelled beans which are resting thereon, vertical tanks or tower constructions are frequently preferred because they are easy to empty by gravity upon the opening of a bottom valve.
2. Discussion of the Prior Art
Different types of leaching or soaking apparatus which are presently employed for extracting or leaching undesired soluble components from various insoluble materials; for instance, comestibles such as beans to render them more digestible or coffee beans for purposes of decaffeination, are also subject to limitations preventing simple operative constructions which, without requiring heavy equipment expenditures, would facilitate a uniform and highly satisfactory degree of soaking and leaching of soluble constituents from insoluble materials on an economical commercial scale of production.
Rector, U.S. Pat. No. 2,309,139 discloses a process and apparatus for decaffeinating coffee in which a leaching or soaking step with the use of a fluid solvent in a downward flow is employed for the extraction of caffeine from the coffee beans and wherein the apparatus basically consists of a vertical columnar extraction unit. This, in essence, consists of the type of apparatus whereby, in its application, crushing of the solids is not particularly problematic, inasmuch as the coffee beans are to be comminuted in subsequent steps. Consequently, there is no critically in maintaining the product in its whole or undamaged physical condition, such as would be required for comestible beans.
Barger, U.S. Reissue Patent No. 31,913 discloses an extraction apparatus in the form of a vertical tower or column for the continuous extraction or leaching of oils and other soluble substances from solid or insoluble materials. This structure employs a vertical flow and sequence of screens for separation of the soluble and insoluble elements of the processed material.
Although various horizontal type of apparatus are also known in the technology for removing soluble constituents from particulate or insoluble materials, these are generally complex in nature and require the provision of a multiplicity of movable parts which would not be desired for the soaking or leaching treatment of relatively delicate comestible beans where it is intended to avoid any damage thereto while rendering the beans more digestible. Moreover, such types of equipment or installations for processing employing movable components are frequently difficult to operate and maintain, inasmuch as the components are subject to wear, and also necessitate a high energy input in order to achieve and maintain the desired soaking, extracting and leaching effects.
Thus, Bushman, U.S. Pat. No. 4,470,344 discloses a horizontal apparatus for the extraction of soluble oils from citrus peel wherein water spray nozzles are adapted to soak the solid components in order to extract the soluble oils therefrom. As illustrated, this horizontal soaking and leaching equipment necessitates the use of numerous movable components such as drive rollers or the like for continuous conveyance of the process materials.
Closmann, U.S. Pat. No. 1,973,247 discloses a horizontal drum for the extraction with liquid and through the steaming of raw unroasted coffee beans, wherein again this equipment necessitates the oscillation or semi-rotation of the drum. In this instance, the coffee beans which are arranged in screened sections in the lower half of the rotatable drum are compressed by upper layers of coffee beans. Although this action may cause some damage to the beans, this may be permissible with regard to coffee beans, but cannot be tolerated during the soaking of whole edible beans for rendering these more digestible through the extraction of solubles, such as oligosaccharides.
Moodie, U.S. Pat. No. 608,554; Swayze, U.S. Pat. No. 2,538,285; Giesse, et al., U.S. Pat. No. 2,703,274; and Rhodes, et al., U.S. Pat. No. 4,234,429, each disclose various types of horizontal leaching installations adapted for the removal of soluble components from particulate materials. However, these publications each utilize a plurality of movable components and drive elements, requiring extensive maintenance and energy consumption in moving the components while causing soluble substances to be leached from subdivided solids through the intermediary of liquids conducted through screens or filters. Basically, the foregoing installations require high levels of energy input in connection with implementing the leaching or soaking processes while operating movable and readily wearable process elements.
In order to clearly and unambiguously provide an installation which has the attendant advantages of being able to deliver high commercial production rates in the soaking of materials and extraction of soluble constituents from the insoluble portions thereof; for instance, extracting sugars from products, such as edible beans, to render them more digestible, the installation incorporates a novel and unique horizontal soak apparatus which eliminates the need for essentially any moving components, and wherein the process of extracting solubles is implemented through the circulation of heated water to soak and swell the beans. A high degree of effectiveness in the design of industrial soak tank equipment of this type is achieved in the attainment of large production capacities. As previously indicated, presently employed soak tanks are limited in throughput capacity by the vertical extents thereof, since taller tower-like tanks are more likely to cause bottommost layers of edible beans to be crushed by the pressure caused by the expansion of the stacked liquid-swelled beans. Although the drawbacks of this type of soak operation for removing solubles are well known in the technology, the vertical tanks are widely used inasmuch as they are easily emptied under gravity by merely the opening of a bottom valve.
As may be evident, it would be economically advantageous to construct large capacity soak tanks possessing lower heights and greater horizontal dimensions in order to avoid beans being subjected to crushing from high stacks of beans, particularly beans which have absorbed soak water and are consequently quite considerably increased in size, with such horizontal soak tanks being essentially known in the art. Subsequent to the beans having absorbed a sufficient amount of soak water, the water-swelled beans and any unabsorbed water containing extracted solubles are discharged. In this case, beans which are more digestible can be readily produced when the water is heated and recirculated through the beans. Nevertheless, a substantially uniform flow of water through a pile of beans is rather difficult to achieve and maintain, and pursuant to the state of the art, practitioners distributed soak water from either top-to-bottom or bottom-to-top through the installations. However, this approach, wherein the bean pile has to be supported by a small holed screen to enable substantially uniform water distribution, and wherein the equipment must possess the necessary physical supportive strength, substantial structural reinforcement is necessary. Such reinforcement, however, has a tendency to block distribution holes and create so-called dead zones downstream or upstream, which disrupt an even flow of the soak or leaching water. For example, a currently employed horizontal soak tank is that of a barley soak tank employed in a brewery, and wherein the goal is merely simple rehydration, reducing such prior art soak tanks to be adequate for their intended use. When it is desirable to produce more digestible beans, and wherein sugars and other solubles in the beans, such as oligosaccharides are to be extracted from the beans in a soak tank, commonly measured as brix-in-soak water, the soaking requirements demand that a careful and consistent time and temperature control over the flow of the soaking liquid, such as water, be implemented to extend substantially uniformly across a bean pile, such concepts are not able to be readily implemented with presently available installations. Thus, one example of a simple measurement of said uniformity of flow includes the temperature distribution across the bean pile following a change in the inlet water temperature. A second measure of the foregoing uniformity is the brix-in-soak water across said bean pile after the leaching of soluble constituents from the comestibles. Pursuant to a preferred embodiment, time temperature and soak water Brix are continuously monitored and employed to control the process.
Pursuant to the present invention, there is accordingly provided a horizontal soak tank for leaching or extracting solubles, such as oligosaccharides from edible beans, wherein the beans would not be crushed during a soak cycle within which each and every bean can be aqueously treated under different temperatures over successive periods of time, and wherein each bean of a charge of beans in the soak tank is imparted an identical treatment so as to provide for the desired uniformity in the soaking and water-absorption of the beans, particularly for the leaching of solubles therefrom, and without evidence of substantially any damage being sustained by the beans during the soak and leaching process in the tank. In order to achieve the foregoing, the horizontal tank is optionally connected to a balance tank for temperature and flow control containing a portion of the soak water to which temperature controls are imparted, in correlation with desired processing requirements, a suitable pumping arrangement facilitates temperature-regulated water to be pumped in laminar flow through the charge of beans in the soak tank, and in continuous flow returned to the balance tank over a specified time period. This soak cycle is repeated under varied conditions, both as to temperature and time, in circulating the flow through the soak tank, until the intended amounts of solubles have been extracted from the beans, rendering the latter potentially more digestible to a consumer, while retaining the desired texture and taste of the beans.
Accordingly, it is an object of the present invention to provide a novel horizontal soak tank facilitating the extraction of solubles from insoluble materials.
Another object of the present invention resides in the provision of a horizontal soak tank for the extraction of soluble constituents from edible beans through the use of a non-laminar flow of water through a screen arrangement in the soak tank.
Yet another object of the present invention resides in the provision of a horizontal soak tank as described herein, wherein soluble constituents comprising oligosaccharides are extracted from beans during a continuous cycle by a non-laminar flow of water through a system of screens in the soak tank in a sequence of controlled temperature, flow and time conditions.
A further object of the present invention resides in the provision of a method of extracting soluble constituents from edible beans utilizing the novel horizontal soak tank as described herein.